<!DOCTYPE html>
<html lang="zh-CN">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>弧形选项卡</title>
  <style>
    .box {
      width: 150px;
      height: 40px;
      margin: 10px auto;
      position: relative;
      text-align: center;
      line-height: 40px;
      color: white;
    }

    .tab {
      background-color: #f00;
      border-radius: 10px 10px 0 0;
      position: absolute;
      inset: 0;
      transform: perspective(30px) rotateX(22deg);
      /* transform-origin: center bottom; */
      z-index: -1;
    }

    .tab::after,
    .tab::before {
      position: absolute;
      content: "";
      width: 10px;
      height: 10px;
      bottom: 0;
    }

    .tab::after {
      left: -10px;
      background: radial-gradient(circle at 0 0, transparent 10px, #f00 10px);
    }

    .tab::before {
      right: -10px;
      background: radial-gradient(circle at 100% 0, transparent 10px, #f00 10px);
    }
  </style>
</head>

<body>
  <div class="box">
    <div class="tab"></div>
    <span>选项1</span>
  </div>
</body>

</html>